It has also been said that Siddhas are group of people who have attained 'siddhi'. The term 'siddhi' means "the attainment of flawless identity with Reality (Bramha); perfection of Spirit."
Origin of Siddha
Siddhas are believed to belong to the fourth root-race datable to 4000 BCE. According to the Shvetashvatara Upanishad Siddhas are born of superhuman powers. Siddhas are cited also in the Indian Puranas grouping with the 'devarishis'. The names of the traditional Siddhas are Agastya, Tirumular, Bogar, Agappei, Pampatti etc. The Siddhas lived in the company of nature and involved themselves in the native system.
Jain Cosmology states that Siddha-Shila is situated at the top of the Universe. The Siddhas or the independent and liberated souls go to the Siddha-Shila as they are free from any terrene bindings of day to day life. The Siddhas are believed to stay there till infinity. Such liberated souls never take a second birth. Siddha is a state of soul above 'Arihanta'.
According to the Hindu Cosmology, Siddha-Shila or Siddha- lokam is a place where the Siddhas born. At the very time of birth the Siddhas are conferred with eight primary siddhis.
As per the Hindu Theology, Siddhashrama is a place or 'ashrama' where great yogis, sadhus, and sages used to reside. Siddhashrama is mentioned in the Ramayanaand Mahabharata also. Viswamitra in Ramayana had his hermitage in Siddhashrama the erstwhile hermitage of Lord Vishnu, when he appeared as the Vamana avatar. In the Narada Puran Siddhashrama is mentioned as the hermitage of sage Suta. It is usually a secret and deep land in the Himalayas. The concept of Siddhashrama resembles the Tibetan mystical land of Shambhala.
Siddha and Tantra
The Siddhas actively work for the development of Shakti Cult which is connected with Tantrism. The Tantrism is originated in Indian and has been spread to China and the Siddhas played a great role in such propagation. The Tirumular contents are notably tantra oriented which describes different chakras in yogic approach.
Tamil Nadu Tradition of Siddhahood
In Tamil Nadu the Siddhas are a group of thinkers achieving a high degree of physical as well as spiritual perfection. This is usually accomplished only by persistent meditation. Thus siddha, like siddhar or cittar refers to a person who has realised the goal of a type of sadhana and become a perfected being united with Bramha. In Tamil Nadu, South India, the siddha tradition is still practiced. There special individuals are recognized as and called Siddhas (or Siddhars or Cittars) being on the path of perfection after they have taken special secret rasayanas to perfect their bodies. They are able to attain this through prolonged meditation along with a form of pranayama which considerably reduces the number of breaths they take.
Different Sampradayas of Siddha
A Siddha may mean a mahasiddha or a natha. Whenever a Siddha is mentioned the eighty four Siddhas and nine nathas are remembered. But in the manuscript found there are only seventy six names of Siddhas are mentioned. They are Minanatha, Gorakshanatha, Chauranginatha, Chamarinatha, Tantipa, Halipa, Kedaripa, Dhongapa, Daripa, Virupa, Kapali, Kamari, Kanha, Kanakhala, Mekhala, Unmana, Kandali, Dhovi, Jalandhara, Tongi, Mavaha, Nagarjuna, Dauli, Bhishala, Achiti, Champak, Dhentasa, Bhumbhari, Bakali, Tuji, Charpati, Bhade, Chandana, Kamari, Karavat, Dharmapapatanga, Bhadra, Patalibhadra, Palihiha,, Bhanu, Mina, Nirdaya, Savara, Santi, Bhartrihari, Bhishana, Bhati, Gaganapa, Gamara, Menura, Kumari, Jivana, Aghosadhava, Girivara, Siyari, Nagavali, Bibhavat, Saranga, Vivikadhaja, Magaradhaja, Achita, Bichita, Nechaka, Chatala, Nachana, Bhilo, Pahila, Pasala, Kamalakangari, Chipila, Govinda, Bhima, Bhairava, Bhadra, Bhamari, Bhurukuti.
Siddha medical system is a form of medical treatment using substitute of all possible origins keeping away the possible harmful effects. This process of medical practices was written on palm leaves for the help of future generations. Siddha medicine was developed by outstanding Dravidians (ancient Tamils), locally called Cittars. This medicinal way is still popular in Southern part of India. The powder form of gold, silver and ironmetals are used in some preparation of medicine. Siddha medicine claims to cure the stubborn diseases.